Workpiece implantation and handling systems are sophisticated systems that are employed in fabricating semiconductor devices including flash memory, system on chip devices, central processor units, and the like. Ion implantation systems are employed during semiconductor device fabrication to selectively implant ions and control device behavior in a process referred to as ion implantation. Ion implantation systems rely on proper performance of their constituent parts in order to properly perform ion implantation and, as a result, properly fabricate semiconductor devices.
Shortening cycle times to fabricate semiconductors is critical to the success of semiconductor manufacturing. A key factor in cycle time is the movement or handling of semiconductor workpieces throughout the process. Shortened cycle times are critical to operational success allowing lean manufacturing, lean inventory, better yields, reducing equipment downtime, and the like. Workpiece presence detection is critical for the robustness of workpiece handling in an ion implantation system and during workpiece manufacturing throughput.
Current workpiece presence sensing technology includes mechanical actuated sensors, laser reflective sensors, optical reflective sensors, proximity sensors and optical interrupt sensors. Each of these sensing methods, mentioned supra, has shortcomings, mainly particle generation and sensing uncertainty.
Mechanical actuated sensors generally require a switch, a plunger, a lever, or other actuator that makes contact with the workpiece in order to engage or activate the sensor. Unfortunately, the contact with the workpiece tends to generate particles and in addition, there is an uncertainty of how well the workpiece is held within the gripper of the handling mechanism, for example. In addition, laser reflective sensors, optical reflective sensors, and optical interrupt sensors only indicate that the workpiece is in a given position, as there is a disconnect between the sensor and the actual gripper-to-wafer contact.
The previously mentioned sensors do not provide complete information on the workpiece to gripper interaction, which leaves uncertainty as to how well the workpiece is actually gripped. Also, optical interrupt sensors generally overhang the workpiece, which is unacceptable in some cases where space is limited.
Thus, it is desirable to provide a method for allowing the detection of the gripping integrity of workpieces within fabrication, ionization, and handling processes.